WiFi, also termed WLAN, has become a ubiquitous wireless technology for data communication in the unlicensed radio spectrum. The Institute of Electrical and Electronic Engineers, IEEE, standard IEEE 802.11 defines the protocol stack and functions used by WiFi access points, APs. In the licensed radio spectrum 3rd generation partnership project, long term evolution, 3GPP LTE, wireless communication technology is rapidly being deployed. LTE is the 4th generation of wireless cellular communications. The protocol stack of LTE is currently defined by the 3GPP. The rapid increase in cellular data usage has prompted wireless operators to turn to using WiFi as a means to offload traffic from the congested licensed radio spectrum.
WiFi and cellular radio networks have traditionally by implemented and operated separately from one another. For example, FIG. 1 shows a known cellular radio network 10 and a known WiFi network 20. Each of networks 10 and 20 are independent of the other, even though coverage provided by each network 10 and 20 may overlap in some areas. The cellular radio network includes a plurality of base stations 12 that contain radios that communicate over a defined geographic area called a cell. The base stations 12 may be, for example, evolved Node B, eNB, base stations of an evolved Universal Terrestrial Radio Access Network, eUTRAN, or LTE network. The air interface of the base stations 12 may be orthogonal frequency division multiple access, OFDMA, on the downlink, and single carrier frequency division multiple access, SC-OFDMA, on the uplink.
Each base station 12 may be in communication with a serving gateway S-GW 14 using an S1 protocol. The S-GW 14 is a communication interface between the base stations 12 and the Internet and/or a backhaul network. As such S-GW 14 routes and forwards user data packets, while also acting as the mobility anchor for the user plane during inter-eNB handovers and as the anchor for mobility between LTE and other 3GPP technologies.
The base stations 12 are also in communication with a mobile management entity, MME, 16. The MME 16 is a control node for an LTE access-network. The MME 16 is responsible for idle mode UE 24, User Equipment, tracking and paging procedures including retransmissions. The MME 16 is involved in the bearer activation/deactivation process and is also responsible for choosing the S-GW 14 for a UE 24 at the UE's initial entry into the LTE network and at a time of intra-LTE handover.
The MME 16 is responsible for authenticating the user, for generation and allocation of temporary identities to UEs, for authorization of the UE 24 to camp on the service provider's Public Land Mobile Network (PLMN) and enforces UE roaming restrictions. The MME is the termination point in the network for ciphering/integrity protection for non-access stratum, NAS, signaling and handles security key management. Lawful interception of signaling is also supported by the MME 16. Further, the MME 16 also provides the control plane function for mobility between LTE and second generation/third generation, 2G/3G, access networks.
The WiFi network 20 includes wireless access points 22. Each WiFi access point functions as a communication interface between a user equipment 24, such as a computer, and the Internet. The coverage of one or more (interconnected) access points—called hotspots—can extend from an area as small as a few rooms to as large as many square miles. Coverage in the larger area may require a group of access points with overlapping coverage.
Cellular radio networks, such as the communication network 10, and the WiFi network 20 utilize two independent radio air interfaces and networks, each with their own operations, administration and management, OAM, infrastructure. Since the two network architectures are separated, the ability to perform fast and reliable mobility (handoff) of subscriber data sessions between the two networks is severely limited. For example, seamless roaming from LTE to WiFi and back without loss of data packets is a hugely complex task with today's separate networks.
The vast majority of smartphone devices now manufactured include both 3GPP cellular (3G and 4G) and WiFi capabilities. These user equipment 24 have separate radio and protocol stacks for each technology (termed dual stack or dual radio). Both wireless technologies operate simultaneously and independently. There is no method for the cellular radio network to know the radio status of the WiFi link. As such, the cellular radio network cannot make any admission, mobility or load balancing decisions with respect to use of the WiFi link.